8. For instance, Patricia Gowaty is the editor of the 1997 book Feminism and Evolutionary Biology: Boundaries, Intersections, and Frontiers as well as other scholarly publications in this area.
9. Snyder, B. F., & Gowaty, P. A. (2007). A reappraisal of Bateman’s classic study of intrasexual selection. Evolution, 61(11), 2457–2468. Quoted on pp. 2458 and 2457, respectively.
10. In fact, a later attempt to replicate Bateman’s study (by Patricia Gowaty and her colleagues) challenged Bateman’s assumption that there would be a quarter-share each of offspring with a maternal mutation only, paternal mutation only, a double mutation, and no mutation. Double-mutation flies, in particular, were particularly unlikely to survive. Gowaty, P. A., Kim, Y.-K., & Anderson, W. W. (2012). No evidence of sexual selection in a repetition of Bateman’s classic study of Drosophila melanogaster. Proceedings of the National Academy of Sciences, 109(29), 11740–11745.
11. Snyder & Gowaty (2007), ibid.
12. Tang-Martínez, Z., & Ryder, T. B. (2005). The problem with paradigms: Bateman’s worldview as a case study. Integrative and Comparative Biology, 45(5), 821–830. They also noted that the mating behaviour of inbred strains may not have been representative of that seen in normal animals. Additionally, a longer experiment might have yielded different findings, since females can store sperm for a number of days, and only reach sexual maturity at about four days of age (compared with one day for males).
13. Tang-Martínez & Ryder (2005), ibid. Quoted on p. 821.
14. Snyder & Gowaty (2007), ibid., report that “Apparently, Bateman’s sole rationale for graphing these series separately was that ‘…series 5 and 6 differed somewhat from the rest’ [Bateman, 1948, p. 361]. This was neither a legitimate nor an a priori justification. Bateman goes on to note that series 5 and 6 were different from series 1–4 because the flies in series 5 and 6 were derived from crosses with inbred strains. However, series 4 was derived from inbred lines in a similar way, and, all six series differed in important ways including the number of flies in each population.” Quoted on p. 2463.
15. Tang-Martínez (2010), ibid. Quoted on p. 168.
16. Synder & Gowaty (2007), ibid. Quoted on p. 2463.
17. See Tang-Martínez (2010), ibid.
18. See Table 1 in Gerlach et al. (2012), with examples from invertebrates, birds, fish, amphibians, reptiles, and mammals, for which female reproductive success is positively associated with multiple mating. Gerlach, N. M., McGlothlin, J. W., Parker, P. G., & Ketterson, E. D. (2012). Reinterpreting Bateman gradients: Multiple mating and selection in both sexes of a song-bird species. Behavioral Ecology, 23(5), 1078–1088.
19. Schulte-Hostedde, A. I., Millar, J. S., & Gibbs, H. L. (2004). Sexual selection and mating patterns in a mammal with female-biased sexual size dimorphism. Behavioral Ecology, 15(2), 351–356; Williams, R. N., & DeWoody, J. A. (2009). Reproductive success and sexual selection in wild eastern tiger salamanders (Ambystoma t. tigrinum). Evolutionary Biology, 36(2), 201–213. Examples provided in Tang-Martínez (2016), ibid.
20. Imhof, M., Harr, B., Brem, G., & Schlötterer, C. (1998). Multiple mating in wild Drosophila melanogaster revisited by microsatellite analysis. Molecular Ecology, 7(7), 915–917.
21. Clapham, P. J., & Palsbøll, P. J. (1997). Molecular analysis of paternity shows promiscuous mating in female humpback whales (Megaptera novaeangliae, Borowski). Proceedings of the Royal Society of London B: Biological Sciences, 264(1378), 95–98.
22. Soltis, J. (2002). Do primate females gain nonprocreative benefits by mating with multiple males? Theoretical and empirical considerations. Evolutionary Anthropology, 11(5), 187–197. Quoted on p. 187.
23. See Chapter 4 of Zuk, M. (2002). Sexual selections: What we can and can’t learn about sex from animals. Berkeley: University of California Press.
24. Lanctot, R. B., Scribner, K. T., Kempenaers, B., & Weatherhead, P. J. (1997). Lekking without a paradox in the buff-breasted sandpiper. The American Naturalist, 149(6), 1051–1070.
25. Lanctot et al. (1997), ibid. Quoted on p. 1059. As the researchers point out, these findings help to explain an apparent paradox of leks, which is why females should continue to exercise choice, despite (presumably) minimal genetic variation in male traits (due to almost all females breeding with the same male).
26. Hrdy (1986), ibid. See also citations in, for example, Tang-Martínez & Ryder (2005), ibid.
27. Hrdy (1986), ibid. Quoted on p. 135.
28. See p. 27 of Fuentes, A. (2012). Race, monogamy, and other lies they told you: Busting myths about human nature. Berkeley: University of California Press.
29. Hrdy (1986), ibid. Quoted on p. 137.
30. Brief overview provided in Knight (2002), ibid. For primates, see discussion in Soltis (2002), ibid. For a discussion of the potential genetic benefits of multiple matings for females, see Jennions, M., & Petrie, M. (2000). Why do females mate multiply? A review of the genetic benefits. Biological Reviews, 75(1), 21–64.
31. A point made by Hrdy (1986), ibid.
32. This latter possibility will be obscured by shorter-term studies as Hrdy (1986), ibid., points out. See also Stockley, P., & Bro-Jørgensen, J. (2011). Female competition and its evolutionary consequences in mammals. Biological Reviews, 86(2), 341–366.
33. See Table 1 in Stockley & Bro-Jørgensen (2011), ibid., p. 345.
34. Stockley & Bro-Jørgensen (2011), ibid. Quoted on p. 344. They note, however, that not all studies have found this effect, although in some cases this may have been because the populations under study were particularly well resourced.
35. For example, Blomquist, G. (2009). Environmental and genetic causes of maturational differences among rhesus macaque matrilines. Behavioral Ecology and Sociobiology, 63(9), 1345–1352.
36. A point made by both Hrdy (1986), ibid., and Stockley & Bro-Jørgensen (2011), ibid.
37. This point is made by a number of authors, including Baylis, J. (1981). The evolution of parental care in fishes, with reference to Darwin’s rule of male sexual selection. Environmental Biology of Fishes, 6(2), 223–251; Dewsbury, D. (1982). Ejaculate cost and male choice. The American Naturalist, 119(5), 601–630; Dewsbury (2005), ibid.; and Tang-Martínez & Ryder (2005), ibid.
38. With considerable variability: Cooper, T. G., Noonan, E., von Eckardstein, S., Auger, J., Baker, H. W., Behre, H. M., et al. (2010). World Health Organization reference values for human semen characteristics. Human Reproduction Update, 16(3), 231–245.
39. Tang-Martínez & Ryder (2005), ibid. Quoted on p. 824.
40. Michalik, P., & Rittschof, C. C. (2011). A comparative analysis of the morphology and evolution of permanent sperm depletion in spiders. PloS One, 6(1), e16014. Cited in Tang-Martínez (2016), ibid.
41. A point made by Dewsbury (1982), ibid.
42. See Dewsbury (1982), ibid.
43. Tang-Martínez (2010), ibid. Quoted on p. 174.
44. For example, see Table 3, p. 318, of Wedell, N., Gage, M. J. G., & Parker, G. A. (2002). Sperm competition, male prudence and sperm-limited females. Trends in Ecology and Evolution, 17(7), 313–320.
45. Renfree, M. (1992). Diapausing dilemmas, sexual stress and mating madness in marsupials. In K. Sheppard, J. Boubilik, & J. Funder (Eds.), Stress and reproduction (pp. 347–360). New York: Raven Press. Both castrated males in the field, and those prevented from mating in the lab, survive substantially beyond the typical life span.
46. Elgar, M. (personal communication on August 6, 2015).
47. Alavi, Y., Elgar, M. A., & Jones, T. M. (2016). Male mating success and the effect of mating history on ejaculate traits in a facultatively parthenogenic insect (Extatosoma tiaratum). Ethology, 122, 1–8.
48. August, C. J. (1971). The rôle of male and female pheromones in the mating behaviour of Tenebrio molitor. Journal of Insect Physiology, 17(4), 739–751; Gwynne, D. T. (1981). Sexual difference theory: Mormon crickets show role reversal in mate choice. Science, 213(4509), 779–780; Pinxten, R., & Eens, M. (1997). Copulation and
mate-guarding patterns in polygynous European starlings. Animal Behaviour, 54(1), 45–58.
49. Gowaty, P. A., Steinichen, R., & Anderson, W. W. (2003). Indiscriminate females and choosy males: Within- and between-species variation in Drosophila. Evolution, 57(9), 2037–2045.
50. Wade, M., & Shuster, S. (2002). The evolution of parental care in the context of sexual selection: A critical reassessment of parental investment theory. The American Naturalist, 160(3), 285–292. See Kokko, H., & Jennions, M. (2003). It takes two to tango. Trends in Ecology and Evolution, 18(3), 103–104.
51. Kokko, H., & Jennions, M. D. (2008). Parental investment, sexual selection and sex ratios. Journal of Evolutionary Biology, 21(4), 919–948. Quoted on p. 926.
52. Emlen, D. J. (1997). Alternative reproductive tactics and male-dimorphism in the horned beetle Onthophagus acuminatus (Coleoptera: Scarabaeidae). Behavioral Ecology and Sociobiology, 41(5), 335–341. With thanks to John Dupré for alerting me to this example.
53. Drea, C. M. (2005). Bateman revisited: The reproductive tactics of female primates. Integrative and Comparative Biology, 45(5), 915–923. Quoted on p. 920, references removed. Nor does parental care seem to be strongly tied to monogamy, a system in which males would have more certainty of paternity. See also Wright, P. C. (1990). Patterns of paternal care in primates. International Journal of Primatology, 11(2), 89–102.
54. Indeed, some biologists have argued that “sex role” is no longer a useful concept. For example, Ah-King, M., & Ahnesjö, I. (2013). The “sex role” concept: An overview and evaluation. Evolutionary Biology, 40(4), 461–470; Roughgarden, J. (2004). Evolution’s rainbow: Diversity, gender, and sexuality in nature and people. Berkeley: University of California Press.
55. Gwynne, D. T., & Simmons, L. W. (1990). Experimental reversal of courtship roles in an insect. Nature, 346(6280), 172–174.
56. Forsgren, E., Amundsen, T., Borg, A. A., & Bjelvenmark, J. (2004). Unusually dynamic sex roles in a fish. Nature, 429(6991), 551–554. Quoted on p. 553.
57. Davies, N. (1992). Dunnock behaviour and social evolution. Oxford, UK: Oxford University Press. Quoted on p. 1.
58. See Davies, N. (1989). Sexual conflict and the polygamy threshold. Animal Behaviour, 38(2), 226–234. Thanks to Mark Elgar for alerting me to this example.
59. Davies (1992), ibid. Quoted on p. 1.
60. Ah-King & Ahnesjö (2013), ibid. Quoted on p. 467, references removed.
61. Itani, J. (1959). Paternal care in the wild Japanese monkey, Macaca fuscata fuscata. Primates, 2(1), 61–93.
CHAPTER 2: ONE HUNDRED BABIES?
1. Einon, D. (1998). How many children can one man have? Evolution and Human Behavior, 19(6), 413–426. Quoted on p. 414. All subsequent references to Einon refer to this citation.
2. Bullough, V. L. (2001). Introduction. In V. L. Bullough, B. Appleby, G. Brewer, C. M. Hajo, & E. Katz (Eds.), Encyclopedia of birth control (pp. xi–xv). Santa Barbara, CA: ABC-CLIO.
3. Bullough (2001), ibid.
4. Schmitt, D. P. (2003). Universal sex differences in the desire for sexual variety: Tests from 52 nations, 6 continents, and 13 islands. Journal of Personality and Social Psychology, 85(1), 85–104. Quoted on p. 87, references removed.
5. Wilcox, A. J., Dunson, D. B., Weinberg, C. R., Trussell, J., & Baird, D. D. (2001). Likelihood of conception with a single act of intercourse: Providing benchmark rates for assessment of postcoital contraceptives. Contraception, 63(4), 211–215. See Figure 1 on p. 212, and accompanying text.
6. This assumes that each coital act was independent—that is, that having sex with Woman A on Tuesday doesn’t affect the probability of conception with Woman B on Wednesday. See also Tuana, N. (2004). Coming to understand: Orgasm and the epistemology of ignorance. Hypatia, 19(1), 194–232.
7. In a later article, Schmitt acknowledges that sex with 100 women would “rarely, if ever” result in 100 offspring. However, he suggests that the odds would be increased by “repeated matings” with the same woman in the fertile period. The plausibility of achieving this feat of carefully timed sexual conquests 100 times is discussed later in the main text. Schmitt, D. P. (2005). Sociosexuality from Argentina to Zimbabwe: A 48-nation study of sex, culture, and strategies of human mating. Behavioral and Brain Sciences, 28(2), 247–275. Quoted on p. 249.
8. The probability of each of the one hundred women having one child (from one coital act), where the probability of clinical pregnancy per coital act is 3.1 per cent and the probability of a live birth from a clinical pregnancy is 90 per cent, assuming independence. Based on data from Wilcox et al. (2001), ibid.
9. For review of such data, see Haselton, M. G., & Gildersleeve, K. (2011). Can men detect ovulation? Current Directions in Psychological Science, 20(2), 87–92.
10. Brewis, A., & Meyer, M. (2005). Demographic evidence that human ovulation is undetectable (at least in pair bonds). Current Anthropology, 46(3), 465–471. Women using chemical contraceptives were excluded from the analysis, and male control of sexual behaviour didn’t affect the results.
11. Laden, G. (September 9, 2011). Coming to terms with the female orgasm. Retrieved from http://scienceblogs.com/gregladen/2011/09/09/coming-to-terms-with-the-femal/ on January 23, 2015.
12. Schmitt later makes the point that a man who has sex with one hundred women will have greater reproductive success than a woman who has sex with one hundred men. This seems reasonable, but the logistics of achieving this given the two- to three-day time frame for identifying and courting the next available woman in the fertile phase of her menstrual cycle seems implausible for most men, to say the least. Schmitt (2005), ibid.
13. The probability of each of the one hundred women having one child (from one coital act) where the probability of a clinical pregnancy per coital act is 8.6 per cent and the probability of a live birth from a clinical pregnancy is 90 per cent, assuming independence. Based on data from Wilcox et al. (2001), ibid, Table 1, p. 213.
14. If you’re reading this book, this hasn’t happened yet. Mann, A. (February 15, 2013). Odds of death by asteroid? Lower than plane crash, higher than lightning. Wired. Retrieved from http://www.wired.com/2013/02/asteroid-odds/ on December 30, 2015.
15. Betzig, L. (2012). Means, variances, and ranges in reproductive success: Comparative evidence. Evolution and Human Behavior, 33(4), 309–317. See Table 1, p. 310.
16. Brown, G. R., Laland, K. N., & Mulder, M. B. (2009). Bateman’s principles and human sex roles. Trends in Ecology and Evolution, 24(6), 297–304.
17. Based on a probability of “success” (that is, birth) on each sexual encounter of 0.9 x 0.031, based on previously used data for these calculations. The probability that the number of “failures” (no baby) observed before 2 successes have occurred will be 136 or less, is 0.9. Or to put it differently, you need to be willing to observe 136 failures for the probability to have observed 2 successes to be 0.9. This is obviously a probabilistic statement—some men might have two “successes” right away—but the probability of this occurring is very low (0.0008). Many thanks to Carsten Murawski for his assistance with this calculation.
18. Drea (2005), ibid. Quoted on p. 916.
19. A point made by Einon (1998), ibid., citing an account of the lack of resource acquisition and status differentials among the !Kung-San, described by Broude, G. J. (1993). Attractive single gatherer wishes to meet rich, powerful hunter for good time under mongongo tree. Behavioral and Brain Sciences, 16(2), 287–289. That hierarchies of wealth are not observed in African foraging societies (like the !Kung San or the Hadza) is also noted by Hrdy, S. B. (2000). The optimal number of fathers: Evolution, demography, and history in the shaping of female mate preferences. Annals of the New York Academy of Sciences, 907(1), 75–96.
20. Fuentes, A. (2005). Ethnography, cultural context, and assessments of reproductive success matter when discussing human mating strategies. Behavioral and Brain Sciences, 28(2), 284–285. Quoted on p. 285.
21. For example, Buss, D. M. & Schmit
t, D. P. (1993). Sexual strategies theory: An evolutionary perspective on human mating. Psychological Review, 100(2), 204–232.
22. Schmitt (2005), ibid. Quoted on p. 249, reference removed.
23. Smiler, A. (2013). Challenging Casanova: Beyond the stereotype of the promiscuous young male. San Francisco, CA: Jossey-Bass. Quoted on p. 1.
24. See also analyses by William C. Pedersen and colleagues. Pedersen, W. C., Miller, L. C., Putcha-Bhagavatula, A. D., & Yang, Y. (2002). Evolved sex differences in the number of partners desired? The long and the short of it. Psychological Science, 13(2), 157–161; Pedersen, W. C., Putcha-Bhagavatula, A., & Miller, L. C. (2011). Are men and women really that different? Examining some of sexual strategies theory (SST)’s key assumptions about sex-distinct mating mechanisms. Sex Roles, 64, 629–643.
25. Alexander, M., & Fisher, T. (2003). Truth and consequences: Using the bogus pipeline to examine sex differences in self-reported sexuality. Journal of Sex Research, 40(1), 27–35.
26. Wiederman, M. (1997). The truth must be in here somewhere: Examining the gender discrepancy in self-reported lifetime number of sex partners. Journal of Sex Research, 34(4), 375–386. Quoted on p. 375. Removing respondents who have participated in paid sex only somewhat reduces the discrepancy between men’s and women’s reports.
27. For instance, Schmitt (2005), ibid., found less “restrained” sociosexuality in males across 48 nations (the sociosexuality measure being an amalgam of behaviours, attitudes, and desires with respect to casual versus committed sex), and greater male interest in having more than one sexual partner over every time period inquired about, from one month to thirty years, and an overall effect size for sex differences in sociosexuality of d = 0.74 (ranging from a low of d = 0.3 in Latvia to a high of d = 1.24 in Morocco and the Ukraine). Similarly, Lippa found an effect size of d = 0.74 with a briefer measure of sociosexuality in a large-scale BBC Internet survey. Lippa, R. A. (2009). Sex differences in sex drive, sociosexuality, and height across 53 nations: Testing evolutionary and social structural theories. Archives of Sexual Behavior, 38(5), 631–651. However, as Eagly and Wood (2005) and Ryan and Jethá (2005) note, Schmitt’s study didn’t include any samples from nonindustrial societies, some of which have more egalitarian gender relations than are seen in any modern, industrialized societies. Eagly, A. H., & Wood, W. (2005). Universal sex differences across patriarchal cultures ≠ evolved psychological dispositions. Behavioral and Brain Sciences, 28(2), 281–283; Ryan, C., & Jethá, C. (2005). Universal human traits: The holy grail of evolutionary psychology. Behavioral and Brain Sciences, 28(2), 292–293. A similar limitation applies to Lippa (2009).
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